This invention relates to a gas seal for preventing or limiting the passage of a gas through an opening, particularly an opening through which solid material also passes. The invention is particularly useful in the continuous preheating of charge materials such as iron-bearing scrap and direct reduced iron for continuous steelmaking in an associated electric arc furnace (EAF).
Continuous steelmaking is particularly advantageous in those regions where there is a concentration of production of, or ready availability of scrap and/or direct reduced iron (DRI), and where electric energy is both available and economical.
The introduction of ambient air to the interior of a chamber frequently places oxygen and/or nitrogen in undesirable contact with the material being heated or treated, resulting in the creation of chemical defects.
Unwanted compounds can be produced during continuous scrap preheating and feeding if the atmosphere within the preheater chamber is not carefully controlled. The present invention is a suitable means for providing such control, and to prevent the introduction of excess oxygen into the chamber.
Historically, the operation of an electric arc steelmaking furnace has been an intermittent operation, wherein the sequence followed is: charging of steel scrap and/or direct reduced iron, pig iron, slag formers and alloying elements; ignition or establishment of an electric arc between the electrodes in the furnace to create melting conditions for melting the charge and forming a molten metal bath covered by a molten slag; refining for a period of time during which the molten metal portion of the bath is refined to form steel having a desired composition and quality; and periodically raising the electrodes to remove them from contact with the bath and interference with the tapping procedure; and then tapping the molten metal. In addition, slag can be removed by a deslagging, or slag-off, operation as required.
The present invention is particularly well suited for use in the continuous steelmaking process described in my U.S. Pat. Nos. 4,543,124 and 4,609,400, which are incorporated herein by reference.